1. Field of the Invention
This invention generally relates to monitoring the quality of satellite communications, and more particularly to a system and method for measuring satellite downline EIRP (Effective Isotropic Radiated Power) power of modulated radio frequency carrier signals.
2. Description of the Related Art
Satellite systems communicate information by establishing uplinks and downlinks between two earth stations on predetermined carrier frequencies. The earth stations may be fixed or mobile and the information may be voice, video, data, or a combination thereof.
In satellite subscriber systems, customers are usually assigned one or more carrier frequencies depending on available capacity. These carrier frequencies are usually contractually agreed to, along with performance parameters including power level. Periodically, system subscribers monitor the EIRP level of their transmissions by requesting such information from a technical operations center of the satellite communications provider. The EIRP level must be acceptable under the terms of the contract or steps must be taken to correct the quality of transmissions.
Conventional methods for measuring EIRP power involve a large number of steps, most of which are manually performed by a technician. These methods first require the technician to access a computer system (Transponder View) containing customer information. From this system, the technician would write down notes indicating the location on the transponder as well as other operational information. The technician would then manually input other information (e.g., frequency, span, reference level) into a spectrum analyzer using a panel keypad on the front of the instrument. Using the spectrum analyzer, the technician measures the bandwidth of a modulated RF carrier signal received from a satellite downlink (typically, at the 3 db points) and then the power level of the carrier signal as compared with a reference carrier, usually 10 dbw in strength.
After taking these measurements, the technician inputs them into a Visual Basic program (known as “SCPC Power”) to achieve a calculated power reading of the modulated data carrier. The measured and calculated power readings are then compared to the contracted information from Transponder View computer system. From this comparison, problems associated with the satellite downlink are determined and subsequently addressed. From this comparison, the technician also determines if the customer's carrier is operating at the proper level. If the customer's carrier is operating at an excessive level in a power-shared transponder, other carriers handled by the transponder could be compressed or otherwise degraded. The customer may also experience degraded service because the carrier is operating at too low of a power level.
There are at least three drawbacks to the conventional methods discussed above. First, these methods require a large number of steps and many of them are manually performed. This makes the measurement process time inefficient, and the substantial involvement of a technician increases costs and introduces the possibility of human error. Second, the conventional methods require the use of separate hardware components, each of which must be manually operated by the technician. This further increases costs and inefficiencies. Third, conventional methods require the use of separate computer programs implemented at different stages of the measurement-taking process. For example, one program is embodied within the Transponder View computer system which a technician must initially access to obtain customer information. Another program is the Visual Basic program which the technician uses to obtain calculated power measurement readings. Using separate programs of this type further increases costs and inefficiencies. Also, the presence of a technician is a necessity because none of these programs “talk” to one another.
From the foregoing discussion, it is apparent that a need exists for a method of the measuring power of a satellite downlink carrier signal which is faster and more efficient than conventional methods.